Clinical Feature and Genetics in Rett Syndrome: A Report on Iranian Patients.

Objectives Rett syndrome is characterized by normal development for the first 6-18 months of life followed by the loss of fine and gross motor skills and the ability to engage in social interaction. In most patients, mutations are found in methyl CpG-binding protein 2 (MECP2) gene. We investigated the relation between Rett clinical diagnosis and mutations in MECP2. Materials & Methods Children suspected of Rett syndrome were invited to participate in this study. Twenty-three patients from the Mofid Hospital, Tehran, Iran suffered from classic Rett syndrome diagnostic criteria were enrolled in 2012. The severity of symptoms was assessed for all of them. The peripheral blood samples were collected in EDTA tubes and the genomic DNA was extracted using standard salting out method. The mutation of MEPC2 gene was studied using DNA sequencing method. Results Overall, 11(47.8%) patients had MECP2 gene mutation, while 12 cases (52.2%) had no mutations. Changes in genetics were associated with phenotypical manifestations. The most prevalent mutation was p.v288 mainly associated with partially or uncontrolled seizures. Conclusion For the first time, we studies the Rett syndrome in terms of clinical manifestations and genetic changes in Iran.


Introduction
Rett syndrome is a X-linked progressive brain developmental disorder and one of the most common causes of mental retardation in females first described in the 1960s by Andreas Rett (1).
Girls affected with classic form of Rett syndrome (RTT) seem to have normal development for 6 to 18 months. This course then followed by the loss of acquired fine and gross motor skills and the ability to engage in social interaction. Abnormal stereotypic hand movements may also occur. Rett syndrome primarily affects females and has an incidence of 1:10000 at birth until the age of 12 years (2).
Rett syndrome has two main types: classic and atypical. These two types may be characterized by their symptoms or specific gene mutations, and most patients with Rett syndrome have a classic form (3).
Mutations in the X-linked gene methyl CpGbinding protein 2 (MECP2) have been found in the majority of patients. MeCP2 is a protein that is critical for normal brain function. This protein is involved in maintaining synapses between nerve cells (4).
The mutations in the gene encoding MECP2 are associated with rare familial cases of RTT as well as in the usual sporadic cases of typical RTT (4).
Using modern mutation detection tests, n 70%-80% of patients with typical RTT mutations are found in MECP2 (5). In addition to RTT, mutations in MECP2 have also been identified in cases with no clinical features of RTT.
Mutations are in the X-linked gene MECP2, which  (9).
In addition to MECP2 mutations, cyclin-dependent kinase-like 5 (CDKL5) and Netrin G1, two other genes have recently been known in patients with clinical phenotype of Rett syndrome (10)(11)(12)(13)(14). We felt that Rett syndrome patients were not well studied in Iran. Therefore, we examined these patients based on the two main principals mentioned above to determine the spectrum of mutation in patients with Rett syndrome. Finally, the reaction products were sequenced and examined by Chromas program.

Statistics
Having gathered patients' data and molecular results, descriptive correlation between genotype and phenotype was finally investigated.

Of 27 patients who met the inclusion criteria, 23
accepted to participate in the study. The mean age of 23 included patients in study was 5.2 yr with SD: ±2.13. The minimum and maximum age was 2, and 10 yr, respectively. The age of onset for signs and symptoms was ranged mostly less than 18 months (87%) and only 3 of 23 patients (13%) had shown their signs and symptoms in the range of [18][19][20][21][22][23][24][25][26][27][28][29][30] months. According to the chart brought in methods section, the severity of signs and symptoms were defined from 0 (less sever) to 3 (most sever) pluses (Table 3).
In addition, frequencies for each of signs or  Table   4. Regarding MECP2 gene mutation, 11 patients         Table 5 for an explanation of the details of each mutation.  Table 5 for an explanation of the details of each mutation.

Discussion
In this study, we reported the results of mutational is unknown (21).
The study of genotype-phenotype correlation requires precise investigations in larger group of patients to determine correlation with various types of mutations.
Genotype-phenotype correlation has been investigated, but it is complex by MECP2 gene X-chromosome inactivation. This inactivity allows a mother with a mutation of MECP2 to have a normal phenotype because of skewing of X-chromosome inactivation (22). In contrast to the problems with X-chromosome inactivation, many studies of genotype-phenotype correlations exist (17,22,23). More studies must be carried out to investigate more case to find better conclusions.
In conclusion, our results together with data reported by others allow general conclusions about the MECP2 mutational spectrum and growth/ developmental manifestations or phenotypes.